Since organic light emitting diode (OLED) devices have many prominent performances such as ultra low weight and thickness, low cost, low power consumption, wide visual angle, full solidification, self-luminescence, low driving voltage, and easy realization of flexible display, and the like, OLED devices will become a new generation of flat panel display technology.
An OLED device is a display device that spontaneously illuminates when its luminescent materials are driven with current. Because organic luminescent materials are highly sensitive to temperature, air and moisture, correct packages are of great importance to keep favorable service life and picture quality of OLED devices.
Technologies for packaging small-sized OLED devices includes a technology that employs glass cement for packaging, and this process comprises the corresponding major packaging steps as follows: (1) screen printing glass cement onto a glass cover plate; (2) sintering the glass cement printed onto the glass cover plate; (3) applying UV glue onto the glass cover plate along the periphery of the glass cement; (4) in a cell-assembling chamber, cell-assembling the glass cover plate with a glass back plate formed with an OLED light-emitting element thereon; (5) curing the UV glue between the glass cover plate and the glass back plate using an ultraviolet lamp; and (6) laser-sintering the glass cement between the glass cover plate and the glass back plate after the curing with the ultraviolet lamp and cutting away the UV glue section to complete the packaging process.
During the process of the packaging process described above, the UV glue acts to encapsulate and thus protect the inside of the cell formed by cell-assembling the glass cover plate and the glass back plate that have not yet been laser-sintered, and therefore the UV glue must ensure to have no discontinuity and no poor adhesive bonding at the processing stage after the cell-assembling of the glass cover plate and the glass back plate while before the laser-sintering of the glass cement.
In order to ensure that the UV glue has no discontinuity and no poor adhesive bonding at the processing stage after the cell-assembling of the glass cover plate and the glass back plate while before the laser-sintering of the glass cement, a big difference (typically 95-100 KPa) between the air pressure inside the cell and the air pressure outside the cell is commonly used to ensure the UV glue to be pressed compact and the difference between pressures inside and outside the cell of the OLED device will be generally retained within the range of 95-100 KPa after the packaging of the OLED device is completed according to the above-mentioned packaging process. However, because the glass cement is fragile, the cell is prone to suffer from cracks and damages due to squeeze by the above-mentioned big difference between pressures inside and outside the cell.